Multiple-loop chromatography system

ABSTRACT

An automated chromatography system employs multiple-port rotary valves for sample storage, introduction and collection. Between the corresponding stator ports of a pair of valves, multiple sample loops are connected in series with inlet and outlet ports by rotating the mechanically linked valve rotors. A third mechanically linked rotary valve distributes the output of a chromatography column to a series of independent sample receivers.

United States Patent 1191 Tindle et al.

[ July 10, 1973 3,357,233 12/1967 Roof .Q. ..55/386X [54] MULTIPLE-LOOP CHROMATOGRAPHY SYSTEM 3,524,305 8/ I970 Ives 55/386 [75] Inventors: Roger C. Tindle; David L. stalling,

both of Columbia, Mo. Primary Examiner-John Adee Assigneez The United States of America as Attorney-Ernest S. Cohen and Albert A. Kash1nsk| represented by the Secretary of Interior, Washington, DC. {22] Filed: Feb. 29, 1972 [57] ABSTRACT 21 A 23 2 An automated chromatography system emplo s multi- 1 pp Y ple-port rotary valves for sample storage, introduction and collection. Between the corres ondin stator orts 52 us. (:1. 55/162, 55/197 of a pair of valves multiple sample Yoops conmfcted [51] 7 Int. Cl Bold /08 in series with inlet and outlet ports by rotating the [58] Field Of Search /67, 197, 386, chanicauy linked valve rotors A third mechanically 55/162; 210/31 198 C linked rotary valve distributes the output of a chromatography column to a series of independent sample re- [56] References Cited ceivers UNITED STATES PATENTS 3,135,211 5/1965 Crawford et al, 55/386 x 11 Claims, 3 Drawing Figures 82 DIGITAL m gamgOG CONTROLLER LOAD 54 I6 /00 PULSE 5 7 avPAss I06 DAMPER '48 5,555 F93 [1:351-

L 4 28 MANUAL I SAMPIVELIVOEADING I04 3 r 42 VALVE a 1 T 66 56* m 1 1 ROTARY 40 I SOLENOID 58 ,mn 60 A, SOLVENT 5 64 7 WASTE sol saw 8 6 t U VALVE CONTROL i 1. BOX H2 [l4 PATEN IED'JUL 1 Guns SOLVEN T SAMPLE LOOP sum a or 2 LOAD v 7 FIG. 2

INPUT DRAIN OUTPUT SAMPLE LOOP 1 MULTIPLE-LOOP CHROMATOGRAPHY SYSTEM BACKGROUND OF THE INVENTION DESCRIPTION OF THE PRIOR ART The use of gel permeation techniques for separating pesticides from lipids in tissue extracts significantly improves pesticide residue analysis. However, the long time required to manually process a single tissue sample limits the utility of the process. An automated system is necessary to overcome this limitation.

Most prior equipment for operating chromatographic systems is unsatisfactory for pesticide residue analysis due to excessive complexity and high cost. Many systems are only suitable for use with aqueous solvents and samples. Such systems cannot perform gel permeation chromatography of the type which requires the use of non-aqueous solvents. In many prior systems, samples are introduced from open cups. The volatile solvents employed in gel permeation chromatography preclude the use of these systems. To overcome these deficiencies of the prior art, our invention was made.

SUMMARY OF THE INVENTION Our invention is a system for automated sample cleanup by gel permeation chromatography. The system includes a manual sample loading valve, a solvent source and pump, a remotely controlled sample storage system, a chromatography column, and a remotely controlled sample collection system.

The manual sample loading valve has two alternate operating positions. In one position a loading line is connected in series with the sample storage system and a drain. In this position manual sample loading is performed. Also in this position, the solvent source and pump are connected in series with a by-pass loop and with the chromatography column. In the alternate position of the sample loading valve, the solvent source and pump are in series with the sample storage system and the chromatography column. In this position the loaded samples are introduced into the column' from the sample storage system.

Beyond the chromatography column, the sample collection system distributes the output to either a waste receptacle or to a series of sample receivers. Except for manual loading of the samples, all the sample introduction, separation and collection operations are automatically synchronized by electromechanical controls.

One feature of our invention that contributes significantly to operating speed and efficiency is a multiple position sample storage and collection system. For sample storage a plurality of independent sample loops are connected in parallel across the stator lines of a matched pair of rotary fluid valves. Inlet and outlet lines are connected to the rotors. By mechanically rotating the valves, the inlet and outlet are alternately connected in series with each sample loop for loading,

storage, and discharge. A similar rotary fluid valve is employed in the sample collection system. From a single rotor inlet, the collection valve alternately distributes the samples to an array of stator outlets for distribution to independent receivers. By a mechanical coupling, the storage and collection valves are locked'into synchronism to prevent cross-contamination and insure the maintenance of sample identity.

Therefore, one object of our invention is a system suitable for automated chromatography.

Another object of our invention is a system for automated chromatography, employing a multiple-loop injection and collection system.

These and other objects of our invention are appar-' ent in the remaining specification and drawing.

DESCRIPTION OF THE DRAWING FIG. I is an electromechanical schematic of a chromatography system.

FIG. 2 is a partial flow path schematic of a manual sample loading valve in loading position.

FIG. 3 is a partial flow path schematic of a manual sample loading valve in automatic operating position.

DESCRIPTION OF THE PREFERRED EMBODIMENT An automated chromatography system 10 is shown in FIG. 1. Fluid samples (not shown) are injected into the system through a rubber septum 12 on an input conduit 14. Once loaded, by employing a novel arrangement of rotary sampling valves 20-22 and a rotary collecting valve 24, the system 10 serially operates upon the contents of an array of sample loops 26 without manual intervention. After separation in a chromatography column 16, the samples are collected in independent reservoirs 18.

To load sample loops 26 a manual sample loading valve 28 is set in the first of two alternate positions. The first position connects a flow path shown schematically in FIG. 2'. Using a hypodermic syringe through rubber septum 12, sample solution is injected serially through lines 14, 30 and 32 to a sample loop 26. To insure that the input lines and sample loop are thoroughly rinsed, a 40-60 percent excess of sample is injected. The excess solution flows through an output line 34, an internal loading valve line 36, and out a drain line 38.

When sample loop 26 is filled, loading valve 28 is switched to the second position shown in FIG. 3. In this position the sample loop is connected in series with a solvent reservoir 40 through a conduit 42, a pump 44,

and a conduit 46. At the output of pump 44, a pulse damper 48 damps the pumping action to smooth the flow of solvent. A suitable pulse damper consists of a tubular conduit partially filled with air and closed on the end opposite the pump. From conduit 46 the solvent flows through an internal line 50 in loading valve 28, then to line 32, and sample loop 26. The solvent drives the samplesolution from the loop, through line 34 and through an internal valve line 52 to an output line 54 which feeds into chromatography column 16. In the column a chromatographic separation is performed as explained in our above noted copending application.

In operation of the chromatography system 10, the time required for loading a sample is significantly less than the time the sample resides in column 16. For operating convenience it is desirable to manually load a a chromatographic separation performed automatically on each sample in turn without manual intervention. For this purpose a multiple-loop sample storage system 56 is employed.

Sample storage system 56 includes two rotary valves -22, each having a rotor 58-60 joined to input and output lines 32-34, respectively. Suitable connections are provided to enable the rotors to turn while maintaining a fluid tight seal with the lines. Each rotary valve 20-22 also has a multiple-port stator 62-64, respectively. Between the corresponding stator ports of the two valves a plurality of sample loops 26 are connected. For convenience only four loops are shown, although in practice more are used.

Energized by a rotary solenoid 66, a shaft 68 drives rotors 58 and 60 to alternately connect each loop 26 in series with input line 32 and output line 34. For loading, the rotors are manually indexed to the appropriate position; for introducing the samples into column 16, the rotors are automatically driven. Since both rotors are locked to a common shaft, synchronism is maintained regardless of the operating mode.

After separation in column 16, each sample from a loop 26 is deposited in an independent reservoir 18. From the column, the sample is driven through a line 66 to a pneumatically operated dump-collect valve 68 which directs the sample solution either to a waste receptacle 70 through a line 72, or through a line 74 to rotary collecting valve 24. Valve 24 is similar in construction and operation to valves 20 and 22, having a single input rotor 76 fixed to shaft 68, and a multiple port stator 78. From the stator ports, output lines 80 distribute the sample solution to receivers 18. Since all three rotors of valves 20-24 are fixed to the same shaft 68, operating synchronism is insured.

For automatic chromatographic separation of the sample constituent in each loop 26, a digital controller 82 emits control pulses at appropriate times for operating pump 44, solenoid 66, and dump/collect valve 68. Using well known digital control circuitry, controller 82, through an electric line 84, energizes a valve control box 86 for synchronizing the operations and indicating the function being performed. For sample loading a manual override is incorporated in the control circuit.

In the operating sequence of system 10, the valve control box 86 energizes rotary solenoid 66 through an electric line 88 to position a sample loop 26 between input and output lines 32 and 34. Pump 44 is then activated through an electric line 90 to drive the sample through column 16. At dump/collect valve 68 the desired sample portion is separated from the remainder and from any excess solvent.

Dump/collect valve 68 is pneumatically switched between alternate positions by air, fed from an inlet 92 through lines 94-98. The air supply is controlled by two solenoid operated air valves 100-102 which are, at appropriate times in the separation cycle, energized by control box 86 through electric lines 104-106. With valve 68 in the collect position the desired sample portion passes to rotary valve 24 for distribution to an individual reservoir 18.

Attached to drive shaft 68, two wafer switches 108-110 electrically index shaft position. Switch 108, through an electric line 112, feeds back to control box 86 information relating to the rotor position of the three synchronized valves. At an appropriate time in the system cycle, switch 110 is actuated through a line 1 14 to drive the rotary valves back to starting position, performing an automatic-homing function.

While many equivalent components might be employed in the chromatography system 10, several commercially available components have been found to be particularly suitable. In the preferred embodiment the following components were successfully employed: Pump-Model 15 501-11 Chemical Feed Pump manufactured by Precision Chemical Products Corp., Waltham, Mass. Sample loading valve--Model SV-803l Chemical Sample Injection Valve, manufactured by Chromatronix Incorporated. Rotary valves, switches and solenoid-Model W2 Fluid Switch Wafers, .Solenoid Type WS5-24 with integral wafer switches, all manufactured by Scanivalve, Inc., San Diego, California. Although these valves, switches and solenoid are designed for pressure measurements in aircraft applications, we have found that they adapt suitably for operation in a chromatographic system.

While this invention has been described with reference to a specific preferred embodiment, other more elaborate chromatographic operations could be achieved by the use of additional valves and timers. Mechanical control could be substituted for digital control. Suitable arrangements to regenerate the column could be employed to adapt for ion exchange chromatography. Another possible modification is the addition of two valve wafers for selecting small disposable adsorption columns. These columns would be prepacked with a suitable adsorbent and attached to synchronized rotary valves in the same manner as the sample loops. Further modification to allow use of different solvents at various times during the run could greatly extend the utility of the invention. In view of the many possible modifications within the scope of this disclosure, our invention is limited only by the following claims.

We claim:

1. A chromatography system comprising:

a plurality of independent sample loops,

means for loading a separate fluid sample into each loop, a fluid pump, a chromatography column, means for alternately connecting each sample loop in series with the pump and the chromatography column for injecting the samples into the column,

means for collecting each sample in an independent reservoir,

means for alternately diverting the column .output into the means for collecting or into a waste receptacle, and

means for timing the operating sequence of the elements in the system to automatically perform a series of chromatographic operations upon the separate fluid samples.

2. A chromatography system as claimed in claim 1 in which:

the means for alternately connecting each sample loop in series with the chromatography column includes first and second rotary fluid valves, each rotary valve including a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports,

the plurality of independent sample loops being connected between the corresponding second ports on the first and second valves, and means for synchronously rotating the rotary valves. 3. A chromatography system as claimed in claim 1 in which: i

the means for collecting each sample in an independent reservoir includes a rotary fluid valve with a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports, and means for rotating the rotary valve. 4. A chromatography system as claimed in claim 2 in which:

the means for collecting each sample in an independent reservoir includes a third rotar'y valve with a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports, and means for rotating the third valve in synchronism with the first and second valves. Y 5. A chromatography columnas claimed in claim 2 in which:

the means for synchronously rotating includes a r0.-

tary solenoid. 6. A chromatography system as claimed in claim 3 in which:

the means for rotating is a rotary solenoid. 7. A chromatography system as claimed in claim 4 in which: v

the means for rotating in synchronism includes a rotary solenoid. 8. A chromatography system as claimed in claim 2 in which:

the first and second rotary valves are linked by a common shaft. 9. A chromatography system as claimed in claim 4 in which:

the first, second, and third rotary valves are linked by a common shaft. 10. A chromatography system as claimed in claim 5 in which:

the first and second rotary valves are linked by a common shaft and driven by a common solenoid. 11. A chromatography system as claimed in claim 7 in which: I

the first, second and third rotary valves are linked by a common shaft and driven by a common solenoid. 

1. A chromatography system comprising: a plurality of independent sample loops, means for loading a separate fluid sample into each loop, a fluid pump, a chromatography column, means for alternately connecting each sample loop in series with the pump and the chromatography column for injecting the samples into the column, means for collecting each sample in an independent reservoir, means for alternately diverting the column output into the means for collecting or into a waste receptacle, and means for timing the operating sequence of the elements in the system to automatically perform a series of chromatographic operations upon the separate fluid samples.
 2. A chromatography system as claimed in claim 1 in which: the means for alternately connecting each sample loop in series with the chromatography column includes first and second rotary fluid valves, each rotary valve including a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports, the plurality of independent sample loops being connected between the corresponding second ports on the first and second valves, and means for synchronously rotating the rotary valves.
 3. A chromatography system as claimed in claim 1 in which: the means for collecting each sample in an independent reservoir includes a rotary fluid valve with a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports, and means for rotating the rotary valve.
 4. A chromatography system as claimed in claim 2 in which: the means for collecting each sample in an independent reservoir includes a third rotary valve with a first port and a plurality of independent second ports, with means for alternately connecting the one port in series with each of the independent second ports, and means for rotating the third valve in synchronism with the first and second valves.
 5. A chromatography column as claimed in claim 2 in which: the means for synchronously rotating includes a rotary solenoid.
 6. A chromatography system as claimed in claim 3 in which: the means for rotating is a rotary solenoid.
 7. A chromatography system as claimed in claim 4 in which: the means for rotating in synchronism includes a rotary solenoid.
 8. A chromatography system as claimed in claim 2 in which: the first and second rotary valves are linked by a common shaft.
 9. A chromatography system as claimed in claim 4 in which: the first, second, and third rotary valves are linked by a common shaft.
 10. A chromatography system as claimed in claim 5 in which: the first and second rotary valves are linked by a common shaft and driven by a common solenoid.
 11. A chromatography sYstem as claimed in claim 7 in which: the first, second and third rotary valves are linked by a common shaft and driven by a common solenoid. 